Magnetic Field Energy Dissipation Driven by Relativistic Flows in Force-Free Collisionless Pair Plasmas

Abstract

It is shown by using a 2-dimensional fully relativistic electromagnetic particle-in-cell (PIC) code that a force-free collisionless pair plasma which is stable against collisionless tearing instability becomes unstable when driven by relativistic plasma flows and the magnetic field energy can be strongly dissipated and converted to heat plasmas as well as high-energy particle production. The force-free current sheet becomes unstable against the firehose instability and eventually breaks up into current filaments which are associated with the magnetic reconnection. The energy spectrum in the high-energy region shows an exponential-type law. The interaction process between the force-free collisionless plasmas and the relativistic plasma flows is an important mechanism for understanding the effective magnetic energy conversion, filament structures and high-energy particle production in astrophysical plasmas.